This project consists of the following studies: Study 1. (Collaboration with Dr. Parshad). The effect of culture conditions on karyotypic stability of rodent and human cells in culture. OBJECTIVE: To define those culture conditions that induce or prevent chromosomal instability in cultured cells, to analyze the mechanisms, and to evaluate this type of genetic change as a causative factor in "spontaneous" neoplastic transformation of rodent cells in culture.